Motor-vehicle headlamps are equipped with one or more optical modules that are arranged in a housing closed by an outer lens so as to obtain, as output from the headlamp, one or more light beams. Simplifying, an optical module of the housing in particular comprises a light source, for example a (or more than one) light-emitting diode(s) (LED(s)) that emits (or emit) light rays, and an optical system including one or more lenses and, where appropriate, a reflector, in order to orient the light rays generated by the light source and form the light beam that is output from the optical module.
It is known that certain motor-vehicle headlamps are capable of making the orientation of the light beam vary depending on the needs of the driver of the vehicle. Thus, when the vehicle is cornering, an electronic system on board the vehicle commands a modification of the orientation of the light beam in order to match it to the field of vision of the driver during the manoeuvre. The headlamp then moves the axis of the light beam in the direction of rotation of the vehicle in order to illuminate the road rather than to project the beam straight ahead.
Other known headlamps are able to provide the low-beam and high-beam functions with the same light source. To this end, these headlamps use mechanical means that move an element, called a deflector, in order to cut off a portion of the beam. Furthermore, there is also a low-beam type light designed for motorway driving, the cut-off in the beam of which is slightly higher than that of a conventional low-beam light in order to improve the visibility of the road when the vehicle is being driven on a motorway.
Thus, it would be desirable to be able to control the light rays emitted by the source in order to modify the dimensions of the light beam that is output from the headlamp and to thereby provide all the aforementioned functions.
However, in present-day lighting systems, increased beam resolution is required, and hence the need in terms of number of pixels is great. Thus, the number of light sources, which may range from 1000 to 500000 or even higher, must be large in order to meet this need.
Now, diode matrix-arrays including such a number of sources have a plurality of disadvantages. The first disadvantage is the cost of manufacture of such assemblies, because a chip of large area has a much higher chance of being fabricated on a wafer element containing a defect. This leads to a low manufacturing yield and therefore to a high cost. A second disadvantage is the fragility of such a matrix-array, which means that particular care is required during handling thereof in order to prevent any damage.
In order to avoid this problem, a diode matrix-array meeting the aforementioned needs may be simulated by combining and assembling a plurality of diode matrix-arrays: the diode matrix-arrays are arranged end-to-end.
However, diode matrix-arrays arranged end-to-end do not allow a uniform light beam to be obtained because an interval also appears between the various light beams of the matrix-arrays composing the beam, which interval corresponds to the spacing between the matrix-arrays.
The invention therefore aims to obtain an optical device, in particular for a motor vehicle, that allows a uniform light beam to be projected from pixelized matrix-arrays of light sources that are arranged end-to-end.